Waste heat conducts three stages of distillation. In nature communication, Wang reported that experiments with this combination showed high efficiency for both water and electricity. Wang set up a multi-stage membrane distiller behind conventional solar cells so that electricity generation could naturally shine on the cell.
Photovoltaic cells work best when kept cool which is one of the reasons why floating solar farms are gaining popularity despite the cost of flotation. Just as the lake keeps the floating panels cool, Wang’s distillers can avoid the heat that would otherwise interfere with solar work. Wang tested the off-the-shelf solar cell system and recorded an efficiency of 11 percent – matching what he measured without distillation backing. Meanwhile, its self-made distillers have turned salt solutions into freshwater three times faster than conventional solar steel. The combination of systems saves both land and mounting costs compared to each operating individually.
When water vapor returns to the liquid it is largely clear of its impurities. The heat of condensation released in the first stage is caught in the second and meanwhile, the water evaporates. Meanwhile, heat from packs of solar cells heats saline or contaminated water to encourage evaporation. This allows the unit field to produce much more water than conventional solar cycles and avoids the large energy demand of plants that emit boiling water in this water. “About 50 percent of water withdrawal in the United States and Western Europe is for energy production,” the paper notes. Most existing sources of electricity consume large amounts of water. Boil plenty of water to run coal and gas turbines. Nuclear power plants do the same thing and use more water for cooling.